The last x register and – HP 15c User Manual
Page 35
Section 3: The Memory Stack, LAST X, and Data Storage
35
The LAST X Register and
K
The LAST X register, a separate memory register, preserves the value that
was last in the display before execution of a numeric operation.
*
Pressing
|K (LAST X) places a copy of the contents of the LAST X register
into the display (X-register). For example:
lost
T
t
t
z
Z
z
z
y
Y
y
y
16
X
4
16
4
Keys:
|x
|K
LAST X:
/
4
4
The K feature saves you from having to re-enter numbers you want to
use again (as shown under Arithmetic Calculations With Constants, page
39). It can also assist you in error recovery, such as executing the wrong
function or keying in the wrong number.
For example, suppose you mistakenly entered the wrong divisor in a chain
calculation:
Keystrokes
Display
287
v
287.0000
12.9
+
22.2481
Oops! The wrong divisor.
| K
12.9000
Retrieves from LAST X the last
entry to the X-register (the
incorrect divisor) before +
was executed.
*
Unless that operation was ’, S, or L, which don’t use or preserve the value in the display (X-
register), but instead calculate from data in the statistics storage registers (R
2
to R
7
). For a complete list of
operations which save x in LAST X, refer to appendix B.